migration/block.c

   1 /*
   2  * QEMU live block migration
   3  *
   4  * Copyright IBM, Corp. 2009
   5  *
   6  * Authors:
   7  *  Liran Schour   <lirans@il.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "block/block.h"
  18 #include "qemu/error-report.h"
  19 #include "qemu/main-loop.h"
  20 #include "hw/hw.h"
  21 #include "qemu/queue.h"
  22 #include "qemu/timer.h"
  23 #include "migration/block.h"
  24 #include "migration/migration.h"
  25 #include "sysemu/blockdev.h"
  26 #include "sysemu/block-backend.h"
  27 #include <assert.h>
  28
  29 #define BLOCK_SIZE                       (1 << 20)
  30 #define BDRV_SECTORS_PER_DIRTY_CHUNK     (BLOCK_SIZE >> BDRV_SECTOR_BITS)
  31
  32 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  33 #define BLK_MIG_FLAG_EOS                0x02
  34 #define BLK_MIG_FLAG_PROGRESS           0x04
  35 #define BLK_MIG_FLAG_ZERO_BLOCK         0x08
  36
  37 #define MAX_IS_ALLOCATED_SEARCH 65536
  38
  39 //#define DEBUG_BLK_MIGRATION
  40
  41 #ifdef DEBUG_BLK_MIGRATION
  42 #define DPRINTF(fmt, ...) \
  43     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  44 #else
  45 #define DPRINTF(fmt, ...) \
  46     do { } while (0)
  47 #endif
  48
  49 typedef struct BlkMigDevState {
  50     /* Written during setup phase.  Can be read without a lock.  */
  51     BlockDriverState *bs;
  52     int shared_base;
  53     int64_t total_sectors;
  54     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  55
  56     /* Only used by migration thread.  Does not need a lock.  */
  57     int bulk_completed;
  58     int64_t cur_sector;
  59     int64_t cur_dirty;
  60
  61     /* Protected by block migration lock.  */
  62     unsigned long *aio_bitmap;
  63     int64_t completed_sectors;
  64     BdrvDirtyBitmap *dirty_bitmap;
  65     Error *blocker;
  66 } BlkMigDevState;
  67
  68 typedef struct BlkMigBlock {
  69     /* Only used by migration thread.  */
  70     uint8_t *buf;
  71     BlkMigDevState *bmds;
  72     int64_t sector;
  73     int nr_sectors;
  74     struct iovec iov;
  75     QEMUIOVector qiov;
  76     BlockAIOCB *aiocb;
  77
  78     /* Protected by block migration lock.  */
  79     int ret;
  80     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  81 } BlkMigBlock;
  82
  83 typedef struct BlkMigState {
  84     /* Written during setup phase.  Can be read without a lock.  */
  85     int blk_enable;
  86     int shared_base;
  87     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  88     int64_t total_sector_sum;
  89     bool zero_blocks;
  90
  91     /* Protected by lock.  */
  92     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  93     int submitted;
  94     int read_done;
  95
  96     /* Only used by migration thread.  Does not need a lock.  */
  97     int transferred;
  98     int prev_progress;
  99     int bulk_completed;
 100
 101     /* Lock must be taken _inside_ the iothread lock.  */
 102     QemuMutex lock;
 103 } BlkMigState;
 104
 105 static BlkMigState block_mig_state;
 106
 107 static void blk_mig_lock(void)
 108 {
 109     qemu_mutex_lock(&block_mig_state.lock);
 110 }
 111
 112 static void blk_mig_unlock(void)
 113 {
 114     qemu_mutex_unlock(&block_mig_state.lock);
 115 }
 116
 117 /* Must run outside of the iothread lock during the bulk phase,
 118  * or the VM will stall.
 119  */
 120
 121 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
 122 {
 123     int len;
 124     uint64_t flags = BLK_MIG_FLAG_DEVICE_BLOCK;
 125
 126     if (block_mig_state.zero_blocks &&
 127         buffer_is_zero(blk->buf, BLOCK_SIZE)) {
 128         flags |= BLK_MIG_FLAG_ZERO_BLOCK;
 129     }
 130
 131     /* sector number and flags */
 132     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
 133                      | flags);
 134
 135     /* device name */
 136     len = strlen(bdrv_get_device_name(blk->bmds->bs));
 137     qemu_put_byte(f, len);
 138     qemu_put_buffer(f, (uint8_t *)bdrv_get_device_name(blk->bmds->bs), len);
 139
 140     /* if a block is zero we need to flush here since the network
 141      * bandwidth is now a lot higher than the storage device bandwidth.
 142      * thus if we queue zero blocks we slow down the migration */
 143     if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
 144         qemu_fflush(f);
 145         return;
 146     }
 147
 148     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 149 }
 150
 151 int blk_mig_active(void)
 152 {
 153     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 154 }
 155
 156 uint64_t blk_mig_bytes_transferred(void)
 157 {
 158     BlkMigDevState *bmds;
 159     uint64_t sum = 0;
 160
 161     blk_mig_lock();
 162     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 163         sum += bmds->completed_sectors;
 164     }
 165     blk_mig_unlock();
 166     return sum << BDRV_SECTOR_BITS;
 167 }
 168
 169 uint64_t blk_mig_bytes_remaining(void)
 170 {
 171     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 172 }
 173
 174 uint64_t blk_mig_bytes_total(void)
 175 {
 176     BlkMigDevState *bmds;
 177     uint64_t sum = 0;
 178
 179     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 180         sum += bmds->total_sectors;
 181     }
 182     return sum << BDRV_SECTOR_BITS;
 183 }
 184
 185
 186 /* Called with migration lock held.  */
 187
 188 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 189 {
 190     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 191
 192     if (sector < bdrv_nb_sectors(bmds->bs)) {
 193         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 194             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 195     } else {
 196         return 0;
 197     }
 198 }
 199
 200 /* Called with migration lock held.  */
 201
 202 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 203                              int nb_sectors, int set)
 204 {
 205     int64_t start, end;
 206     unsigned long val, idx, bit;
 207
 208     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 209     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 210
 211     for (; start <= end; start++) {
 212         idx = start / (sizeof(unsigned long) * 8);
 213         bit = start % (sizeof(unsigned long) * 8);
 214         val = bmds->aio_bitmap[idx];
 215         if (set) {
 216             val |= 1UL << bit;
 217         } else {
 218             val &= ~(1UL << bit);
 219         }
 220         bmds->aio_bitmap[idx] = val;
 221     }
 222 }
 223
 224 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 225 {
 226     BlockDriverState *bs = bmds->bs;
 227     int64_t bitmap_size;
 228
 229     bitmap_size = bdrv_nb_sectors(bs) + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 230     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 231
 232     bmds->aio_bitmap = g_malloc0(bitmap_size);
 233 }
 234
 235 /* Never hold migration lock when yielding to the main loop!  */
 236
 237 static void blk_mig_read_cb(void *opaque, int ret)
 238 {
 239     BlkMigBlock *blk = opaque;
 240
 241     blk_mig_lock();
 242     blk->ret = ret;
 243
 244     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 245     bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
 246
 247     block_mig_state.submitted--;
 248     block_mig_state.read_done++;
 249     assert(block_mig_state.submitted >= 0);
 250     blk_mig_unlock();
 251 }
 252
 253 /* Called with no lock taken.  */
 254
 255 static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
 256 {
 257     int64_t total_sectors = bmds->total_sectors;
 258     int64_t cur_sector = bmds->cur_sector;
 259     BlockDriverState *bs = bmds->bs;
 260     BlkMigBlock *blk;
 261     int nr_sectors;
 262
 263     if (bmds->shared_base) {
 264         qemu_mutex_lock_iothread();
 265         while (cur_sector < total_sectors &&
 266                !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
 267                                   &nr_sectors)) {
 268             cur_sector += nr_sectors;
 269         }
 270         qemu_mutex_unlock_iothread();
 271     }
 272
 273     if (cur_sector >= total_sectors) {
 274         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 275         return 1;
 276     }
 277
 278     bmds->completed_sectors = cur_sector;
 279
 280     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 281
 282     /* we are going to transfer a full block even if it is not allocated */
 283     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 284
 285     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 286         nr_sectors = total_sectors - cur_sector;
 287     }
 288
 289     blk = g_new(BlkMigBlock, 1);
 290     blk->buf = g_malloc(BLOCK_SIZE);
 291     blk->bmds = bmds;
 292     blk->sector = cur_sector;
 293     blk->nr_sectors = nr_sectors;
 294
 295     blk->iov.iov_base = blk->buf;
 296     blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 297     qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 298
 299     blk_mig_lock();
 300     block_mig_state.submitted++;
 301     blk_mig_unlock();
 302
 303     qemu_mutex_lock_iothread();
 304     blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
 305                                 nr_sectors, blk_mig_read_cb, blk);
 306
 307     bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, cur_sector, nr_sectors);
 308     qemu_mutex_unlock_iothread();
 309
 310     bmds->cur_sector = cur_sector + nr_sectors;
 311     return (bmds->cur_sector >= total_sectors);
 312 }
 313
 314 /* Called with iothread lock taken.  */
 315
 316 static int set_dirty_tracking(void)
 317 {
 318     BlkMigDevState *bmds;
 319     int ret;
 320
 321     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 322         bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE,
 323                                                       NULL, NULL);
 324         if (!bmds->dirty_bitmap) {
 325             ret = -errno;
 326             goto fail;
 327         }
 328     }
 329     return 0;
 330
 331 fail:
 332     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 333         if (bmds->dirty_bitmap) {
 334             bdrv_release_dirty_bitmap(bmds->bs, bmds->dirty_bitmap);
 335         }
 336     }
 337     return ret;
 338 }
 339
 340 static void unset_dirty_tracking(void)
 341 {
 342     BlkMigDevState *bmds;
 343
 344     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 345         bdrv_release_dirty_bitmap(bmds->bs, bmds->dirty_bitmap);
 346     }
 347 }
 348
 349 static void init_blk_migration(QEMUFile *f)
 350 {
 351     BlockDriverState *bs;
 352     BlkMigDevState *bmds;
 353     int64_t sectors;
 354
 355     block_mig_state.submitted = 0;
 356     block_mig_state.read_done = 0;
 357     block_mig_state.transferred = 0;
 358     block_mig_state.total_sector_sum = 0;
 359     block_mig_state.prev_progress = -1;
 360     block_mig_state.bulk_completed = 0;
 361     block_mig_state.zero_blocks = migrate_zero_blocks();
 362
 363     for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
 364         if (bdrv_is_read_only(bs)) {
 365             continue;
 366         }
 367
 368         sectors = bdrv_nb_sectors(bs);
 369         if (sectors <= 0) {
 370             return;
 371         }
 372
 373         bmds = g_new0(BlkMigDevState, 1);
 374         bmds->bs = bs;
 375         bmds->bulk_completed = 0;
 376         bmds->total_sectors = sectors;
 377         bmds->completed_sectors = 0;
 378         bmds->shared_base = block_mig_state.shared_base;
 379         alloc_aio_bitmap(bmds);
 380         error_setg(&bmds->blocker, "block device is in use by migration");
 381         bdrv_op_block_all(bs, bmds->blocker);
 382         bdrv_ref(bs);
 383
 384         block_mig_state.total_sector_sum += sectors;
 385
 386         if (bmds->shared_base) {
 387             DPRINTF("Start migration for %s with shared base image\n",
 388                     bdrv_get_device_name(bs));
 389         } else {
 390             DPRINTF("Start full migration for %s\n", bdrv_get_device_name(bs));
 391         }
 392
 393         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 394     }
 395 }
 396
 397 /* Called with no lock taken.  */
 398
 399 static int blk_mig_save_bulked_block(QEMUFile *f)
 400 {
 401     int64_t completed_sector_sum = 0;
 402     BlkMigDevState *bmds;
 403     int progress;
 404     int ret = 0;
 405
 406     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 407         if (bmds->bulk_completed == 0) {
 408             if (mig_save_device_bulk(f, bmds) == 1) {
 409                 /* completed bulk section for this device */
 410                 bmds->bulk_completed = 1;
 411             }
 412             completed_sector_sum += bmds->completed_sectors;
 413             ret = 1;
 414             break;
 415         } else {
 416             completed_sector_sum += bmds->completed_sectors;
 417         }
 418     }
 419
 420     if (block_mig_state.total_sector_sum != 0) {
 421         progress = completed_sector_sum * 100 /
 422                    block_mig_state.total_sector_sum;
 423     } else {
 424         progress = 100;
 425     }
 426     if (progress != block_mig_state.prev_progress) {
 427         block_mig_state.prev_progress = progress;
 428         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 429                          | BLK_MIG_FLAG_PROGRESS);
 430         DPRINTF("Completed %d %%\r", progress);
 431     }
 432
 433     return ret;
 434 }
 435
 436 static void blk_mig_reset_dirty_cursor(void)
 437 {
 438     BlkMigDevState *bmds;
 439
 440     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 441         bmds->cur_dirty = 0;
 442     }
 443 }
 444
 445 /* Called with iothread lock taken.  */
 446
 447 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
 448                                  int is_async)
 449 {
 450     BlkMigBlock *blk;
 451     int64_t total_sectors = bmds->total_sectors;
 452     int64_t sector;
 453     int nr_sectors;
 454     int ret = -EIO;
 455
 456     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 457         blk_mig_lock();
 458         if (bmds_aio_inflight(bmds, sector)) {
 459             blk_mig_unlock();
 460             bdrv_drain_all();
 461         } else {
 462             blk_mig_unlock();
 463         }
 464         if (bdrv_get_dirty(bmds->bs, bmds->dirty_bitmap, sector)) {
 465
 466             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 467                 nr_sectors = total_sectors - sector;
 468             } else {
 469                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 470             }
 471             blk = g_new(BlkMigBlock, 1);
 472             blk->buf = g_malloc(BLOCK_SIZE);
 473             blk->bmds = bmds;
 474             blk->sector = sector;
 475             blk->nr_sectors = nr_sectors;
 476
 477             if (is_async) {
 478                 blk->iov.iov_base = blk->buf;
 479                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 480                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 481
 482                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 483                                             nr_sectors, blk_mig_read_cb, blk);
 484
 485                 blk_mig_lock();
 486                 block_mig_state.submitted++;
 487                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 488                 blk_mig_unlock();
 489             } else {
 490                 ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
 491                 if (ret < 0) {
 492                     goto error;
 493                 }
 494                 blk_send(f, blk);
 495
 496                 g_free(blk->buf);
 497                 g_free(blk);
 498             }
 499
 500             bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, sector, nr_sectors);
 501             break;
 502         }
 503         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 504         bmds->cur_dirty = sector;
 505     }
 506
 507     return (bmds->cur_dirty >= bmds->total_sectors);
 508
 509 error:
 510     DPRINTF("Error reading sector %" PRId64 "\n", sector);
 511     g_free(blk->buf);
 512     g_free(blk);
 513     return ret;
 514 }
 515
 516 /* Called with iothread lock taken.
 517  *
 518  * return value:
 519  * 0: too much data for max_downtime
 520  * 1: few enough data for max_downtime
 521 */
 522 static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
 523 {
 524     BlkMigDevState *bmds;
 525     int ret = 1;
 526
 527     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 528         ret = mig_save_device_dirty(f, bmds, is_async);
 529         if (ret <= 0) {
 530             break;
 531         }
 532     }
 533
 534     return ret;
 535 }
 536
 537 /* Called with no locks taken.  */
 538
 539 static int flush_blks(QEMUFile *f)
 540 {
 541     BlkMigBlock *blk;
 542     int ret = 0;
 543
 544     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 545             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 546             block_mig_state.transferred);
 547
 548     blk_mig_lock();
 549     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 550         if (qemu_file_rate_limit(f)) {
 551             break;
 552         }
 553         if (blk->ret < 0) {
 554             ret = blk->ret;
 555             break;
 556         }
 557
 558         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 559         blk_mig_unlock();
 560         blk_send(f, blk);
 561         blk_mig_lock();
 562
 563         g_free(blk->buf);
 564         g_free(blk);
 565
 566         block_mig_state.read_done--;
 567         block_mig_state.transferred++;
 568         assert(block_mig_state.read_done >= 0);
 569     }
 570     blk_mig_unlock();
 571
 572     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 573             block_mig_state.submitted, block_mig_state.read_done,
 574             block_mig_state.transferred);
 575     return ret;
 576 }
 577
 578 /* Called with iothread lock taken.  */
 579
 580 static int64_t get_remaining_dirty(void)
 581 {
 582     BlkMigDevState *bmds;
 583     int64_t dirty = 0;
 584
 585     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 586         dirty += bdrv_get_dirty_count(bmds->dirty_bitmap);
 587     }
 588
 589     return dirty << BDRV_SECTOR_BITS;
 590 }
 591
 592 /* Called with iothread lock taken.  */
 593
 594 static void blk_mig_cleanup(void)
 595 {
 596     BlkMigDevState *bmds;
 597     BlkMigBlock *blk;
 598
 599     bdrv_drain_all();
 600
 601     unset_dirty_tracking();
 602
 603     blk_mig_lock();
 604     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 605         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 606         bdrv_op_unblock_all(bmds->bs, bmds->blocker);
 607         error_free(bmds->blocker);
 608         bdrv_unref(bmds->bs);
 609         g_free(bmds->aio_bitmap);
 610         g_free(bmds);
 611     }
 612
 613     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 614         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 615         g_free(blk->buf);
 616         g_free(blk);
 617     }
 618     blk_mig_unlock();
 619 }
 620
 621 static void block_migration_cancel(void *opaque)
 622 {
 623     blk_mig_cleanup();
 624 }
 625
 626 static int block_save_setup(QEMUFile *f, void *opaque)
 627 {
 628     int ret;
 629
 630     DPRINTF("Enter save live setup submitted %d transferred %d\n",
 631             block_mig_state.submitted, block_mig_state.transferred);
 632
 633     qemu_mutex_lock_iothread();
 634     init_blk_migration(f);
 635
 636     /* start track dirty blocks */
 637     ret = set_dirty_tracking();
 638
 639     if (ret) {
 640         qemu_mutex_unlock_iothread();
 641         return ret;
 642     }
 643
 644     qemu_mutex_unlock_iothread();
 645
 646     ret = flush_blks(f);
 647     blk_mig_reset_dirty_cursor();
 648     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 649
 650     return ret;
 651 }
 652
 653 static int block_save_iterate(QEMUFile *f, void *opaque)
 654 {
 655     int ret;
 656     int64_t last_ftell = qemu_ftell(f);
 657     int64_t delta_ftell;
 658
 659     DPRINTF("Enter save live iterate submitted %d transferred %d\n",
 660             block_mig_state.submitted, block_mig_state.transferred);
 661
 662     ret = flush_blks(f);
 663     if (ret) {
 664         return ret;
 665     }
 666
 667     blk_mig_reset_dirty_cursor();
 668
 669     /* control the rate of transfer */
 670     blk_mig_lock();
 671     while ((block_mig_state.submitted +
 672             block_mig_state.read_done) * BLOCK_SIZE <
 673            qemu_file_get_rate_limit(f)) {
 674         blk_mig_unlock();
 675         if (block_mig_state.bulk_completed == 0) {
 676             /* first finish the bulk phase */
 677             if (blk_mig_save_bulked_block(f) == 0) {
 678                 /* finished saving bulk on all devices */
 679                 block_mig_state.bulk_completed = 1;
 680             }
 681             ret = 0;
 682         } else {
 683             /* Always called with iothread lock taken for
 684              * simplicity, block_save_complete also calls it.
 685              */
 686             qemu_mutex_lock_iothread();
 687             ret = blk_mig_save_dirty_block(f, 1);
 688             qemu_mutex_unlock_iothread();
 689         }
 690         if (ret < 0) {
 691             return ret;
 692         }
 693         blk_mig_lock();
 694         if (ret != 0) {
 695             /* no more dirty blocks */
 696             break;
 697         }
 698     }
 699     blk_mig_unlock();
 700
 701     ret = flush_blks(f);
 702     if (ret) {
 703         return ret;
 704     }
 705
 706     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 707     delta_ftell = qemu_ftell(f) - last_ftell;
 708     if (delta_ftell > 0) {
 709         return 1;
 710     } else if (delta_ftell < 0) {
 711         return -1;
 712     } else {
 713         return 0;
 714     }
 715 }
 716
 717 /* Called with iothread lock taken.  */
 718
 719 static int block_save_complete(QEMUFile *f, void *opaque)
 720 {
 721     int ret;
 722
 723     DPRINTF("Enter save live complete submitted %d transferred %d\n",
 724             block_mig_state.submitted, block_mig_state.transferred);
 725
 726     ret = flush_blks(f);
 727     if (ret) {
 728         return ret;
 729     }
 730
 731     blk_mig_reset_dirty_cursor();
 732
 733     /* we know for sure that save bulk is completed and
 734        all async read completed */
 735     blk_mig_lock();
 736     assert(block_mig_state.submitted == 0);
 737     blk_mig_unlock();
 738
 739     do {
 740         ret = blk_mig_save_dirty_block(f, 0);
 741         if (ret < 0) {
 742             return ret;
 743         }
 744     } while (ret == 0);
 745
 746     /* report completion */
 747     qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 748
 749     DPRINTF("Block migration completed\n");
 750
 751     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 752
 753     blk_mig_cleanup();
 754     return 0;
 755 }
 756
 757 static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
 758 {
 759     /* Estimate pending number of bytes to send */
 760     uint64_t pending;
 761
 762     qemu_mutex_lock_iothread();
 763     blk_mig_lock();
 764     pending = get_remaining_dirty() +
 765                        block_mig_state.submitted * BLOCK_SIZE +
 766                        block_mig_state.read_done * BLOCK_SIZE;
 767
 768     /* Report at least one block pending during bulk phase */
 769     if (pending <= max_size && !block_mig_state.bulk_completed) {
 770         pending = max_size + BLOCK_SIZE;
 771     }
 772     blk_mig_unlock();
 773     qemu_mutex_unlock_iothread();
 774
 775     DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
 776     return pending;
 777 }
 778
 779 static int block_load(QEMUFile *f, void *opaque, int version_id)
 780 {
 781     static int banner_printed;
 782     int len, flags;
 783     char device_name[256];
 784     int64_t addr;
 785     BlockDriverState *bs, *bs_prev = NULL;
 786     BlockBackend *blk;
 787     uint8_t *buf;
 788     int64_t total_sectors = 0;
 789     int nr_sectors;
 790     int ret;
 791
 792     do {
 793         addr = qemu_get_be64(f);
 794
 795         flags = addr & ~BDRV_SECTOR_MASK;
 796         addr >>= BDRV_SECTOR_BITS;
 797
 798         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 799             /* get device name */
 800             len = qemu_get_byte(f);
 801             qemu_get_buffer(f, (uint8_t *)device_name, len);
 802             device_name[len] = '\0';
 803
 804             blk = blk_by_name(device_name);
 805             if (!blk) {
 806                 fprintf(stderr, "Error unknown block device %s\n",
 807                         device_name);
 808                 return -EINVAL;
 809             }
 810             bs = blk_bs(blk);
 811
 812             if (bs != bs_prev) {
 813                 bs_prev = bs;
 814                 total_sectors = bdrv_nb_sectors(bs);
 815                 if (total_sectors <= 0) {
 816                     error_report("Error getting length of block device %s",
 817                                  device_name);
 818                     return -EINVAL;
 819                 }
 820             }
 821
 822             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 823                 nr_sectors = total_sectors - addr;
 824             } else {
 825                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 826             }
 827
 828             if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
 829                 ret = bdrv_write_zeroes(bs, addr, nr_sectors,
 830                                         BDRV_REQ_MAY_UNMAP);
 831             } else {
 832                 buf = g_malloc(BLOCK_SIZE);
 833                 qemu_get_buffer(f, buf, BLOCK_SIZE);
 834                 ret = bdrv_write(bs, addr, buf, nr_sectors);
 835                 g_free(buf);
 836             }
 837
 838             if (ret < 0) {
 839                 return ret;
 840             }
 841         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 842             if (!banner_printed) {
 843                 printf("Receiving block device images\n");
 844                 banner_printed = 1;
 845             }
 846             printf("Completed %d %%%c", (int)addr,
 847                    (addr == 100) ? '\n' : '\r');
 848             fflush(stdout);
 849         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 850             fprintf(stderr, "Unknown block migration flags: %#x\n", flags);
 851             return -EINVAL;
 852         }
 853         ret = qemu_file_get_error(f);
 854         if (ret != 0) {
 855             return ret;
 856         }
 857     } while (!(flags & BLK_MIG_FLAG_EOS));
 858
 859     return 0;
 860 }
 861
 862 static void block_set_params(const MigrationParams *params, void *opaque)
 863 {
 864     block_mig_state.blk_enable = params->blk;
 865     block_mig_state.shared_base = params->shared;
 866
 867     /* shared base means that blk_enable = 1 */
 868     block_mig_state.blk_enable |= params->shared;
 869 }
 870
 871 static bool block_is_active(void *opaque)
 872 {
 873     return block_mig_state.blk_enable == 1;
 874 }
 875
 876 static SaveVMHandlers savevm_block_handlers = {
 877     .set_params = block_set_params,
 878     .save_live_setup = block_save_setup,
 879     .save_live_iterate = block_save_iterate,
 880     .save_live_complete = block_save_complete,
 881     .save_live_pending = block_save_pending,
 882     .load_state = block_load,
 883     .cancel = block_migration_cancel,
 884     .is_active = block_is_active,
 885 };
 886
 887 void blk_mig_init(void)
 888 {
 889     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 890     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 891     qemu_mutex_init(&block_mig_state.lock);
 892
 893     register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
 894                          &block_mig_state);
 895 }